"BBC Worldwide is currently investigating a security issue around Doctor Who series eight where unfinished material has inadvertently been made public," the company told Radio Times in a statement.
"We deeply regret this and apologise to all the show's fans, the BBC and the cast and crew who have worked tirelessly making the series. "We would like to make a plea to anyone who might have any of this material and spoilers associated with it not to share it with a wider audience so that everyone can enjoy the show as it should be seen when it launches.